Waec Model Questions Vol1 2021 Biology Question 6

Practice essay / theory question 6 from the 2021 Waec Model Questions Vol1 Biology examination. This question covers Excretion, Renal physiology .

Waec Model Questions Vol1 2021 Biology Essay / Theory

Topics: Excretion Renal physiology

Question 6 WAEC_MODEL_QUESTIONS_VOL1 • 2021 • BIOLOGY • essay

The human kidney maintains internal homeostasis by filtering blood, re‑absorbing needed substances and excreting waste. The glomerular filtration rate (GFR) in a healthy adult is about 125 mL per minute.

Question Parts

( a )

Describe the pathway of the filtrate from its formation in the renal corpuscle to its exit as urine, naming each major structure it passes through.

( b )

If 99 % of the filtered Na⁺ is re‑absorbed and 65 % of the filtered water is re‑absorbed, calculate the percentage of the filtered volume that appears as urine and the percentage of filtered Na⁺ that is excreted. Show your reasoning.

( c )

Discuss how the counter‑current multiplier system in the loop of Henle contributes to the concentration of urine, and explain why this mechanism is essential for water conservation in humans living in a desert environment.

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About This Question

This is Waec Model Questions Vol1 2021 Biology Question 6. It is one of the essay questions from the 2021 Waec Model Questions Vol1 Biology examination.

The question covers Excretion, Renal physiology .

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